Important progress towards elimination of onchocerciasis in the West Region of Cameroon

Abstract

BackgroundAfter more than a decade of community-directed treatment with ivermectin (CDTI) in the West Region of Cameroon, epidemiological evaluation conducted in 2011 showed that onchocerciasis endemicity was still high in some communities. The conceptual framework for onchocerciasis elimination recommends in such case, to conduct additional phase 1A surveys at intervals of three to four years. Therefore, to assess the progress made towards the elimination of onchocerciasis in the West CDTI projects, we conducted a cross-sectional survey in May 2015 in 15 unevaluated communities where the highest baseline endemicity level were found in 1996. All volunteers living for at least five years in the community, aged five years or more, underwent clinical and parasitological examinations. Individual adherence to ivermectin treatment was also assessed. Analyses of data were weighted proportionally to age and gender distribution in the population.ResultsThe mean age was 28.4 ± 22.2 years and there were 55% of women among the 2058 individuals examined. The weighted prevalences were 5.5%, 2.1% and 1.7% for microfilaridermia, nodule and cutaneous signs, respectively. The weighted microfilaridermia prevalences varied from 4.0 in 5–9 years old to 11.6% in 40–49 years old. In the 30 children under 10 years examined in Makouopsap, the weighted prevalences were 49.9% for microfilaridermia and 13.3% for nodule. In surveyed communities, the weighted prevalences varied from 0 to 41.6% for microfilaridermia, with 11 (73.3%) communities having <5%. Except Makouopsap which had 41.6%, all the surveyed communities were below 15% for microfilaridermia prevalence. The community microfilarial load (CMFL) expressed in microfilariae/skin snip (mf/ss), also significantly dropped by 98–100%, from 3.75–33.16 mf/ss in 1996 to 0–0.94 mf/ss in 2015. The weighted therapeutic coverage in 2014 was 69.4% and the 5 years’ adherence was only 39.3% among participants.ConclusionsAfter more than 15 years of CDTI, there is an important progress towards the elimination of onchocerciasis in the communities surveyed. Innovative strategy like semi-annual ivermectin treatment plus vector control or the adjunction of a vector control strategy to the current annual treatment should be implemented in the bordering districts of the Centre and West Regions, as well as in other parts of the country with persistent high prevalences in the sight of onchocerciasis elimination.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-017-2301-7) contains supplementary material, which is available to authorized users.

Prediction and validation of the structural features of Ov58GPCR, an immunogenic determinant of Onchocerca volvulus

“…The goal of the experiment was to assess the effects of drug treatment on antigen-specific antibodies in the microfilaria-negative individuals. These 3 targeted communities were previously reported with high microfilaridermia (>80%) [ 13 ]. Following around 20 years of IVM MDA, the results of the studies carried out in 2015 [ 13 ] motivated us to select the three communities for the above objective in this study.…”

“…These 3 targeted communities were previously reported with high microfilaridermia (>80%) [ 13 ]. Following around 20 years of IVM MDA, the results of the studies carried out in 2015 [ 13 ] motivated us to select the three communities for the above objective in this study. Serum samples from individuals from all three communities were used in this assay.…”

“…These 3 selected communities with near-elimination were all previously hyperendemic based on results from baseline data in 1996 (with weighted microfilaridermia prevalence values of >80%). The follow-up weighted microfilaridermia values in 2015 in these communities was 10% for Se Dembom and 0% for Lemgo and Tsesse [ 13 ]. Annual mass treatment with ivermectin commenced in this health district in 1996.…”

“…Control programmes have achieved some successes: eliminating the disease in 4 of 6 endemic countries in the Americas and in selected foci in Africa [ 10 – 13 ]. These successes have led to the shift in treatment goals of onchocerciasis from control of morbidity to elimination [ 14 ].…”

Onchodermatitis: Where Are We Now?

“…The weighted prevalence of skin disease excluding nodules was 1.7% and varied from 1.1% in men to 2.2% in women. Of note, treatment compliance was again found to be poor with only 39.3% of participants declaring they had taken five treatments during the last five years [ 66 ].…”